Under Armour's UA Freedom HeatGear Armour tactical short sleeve shirt is made from a 4-way stretch polyester/Elastane blend that is very smooth, providing extreme comfort and powerful compression without restricting your movement. It uses the signature Under Armour Moisture Transport System to wick sweat away from your skin, and anti-odor technology that prevents the growth of odor causing microbes. The fabric also has a 30+ UPF rating to protect your skin from the sun.